Harvard Psychological Studies, Volume 1 eBook

such stimuli as light and the relation of the opening
to the place at which the animals were put into the
box might in themselves be sufficient to direct the
animals to this point without the help of any associations
which had resulted from previous experience, makes
it unsatisfactory. In addition to the possibility
of the action being due to specific sensory stimuli
of inherent directive value, there is the chance of
its being nothing more than the well-known phenomenon
of repetition. Frogs, for some reason, tend to
repeat any action which has not proved harmful or
unpleasant.

For the purpose of more carefully testing this kind
of association, a small box with an opening 15 cm.
by 10 cm. was arranged so that the animal could escape
from confinement in it through the upper part of the
opening, the lower portion being closed by a plate
of glass 10 cm. by 10 cm., leaving a space 5 cm. by
10 cm. at the top. One subject placed in this
box escaped in 5 minutes 42 seconds. After 5 minutes’
rest it was given another trial, and this time got
out in 2 minutes 40 seconds. The times for a
few subsequent trials were: Third, 1 minute 22
seconds; fourth, 4 minutes 35 seconds; fifth, 2 minutes
38 seconds; sixth, 3 minutes 16 seconds. Although
this seems to indicate some improvement, later experiments
served to prove that the frogs did not readily form
any associations which helped them to escape.
They tended to jump toward the opening because it
was light, but they did not learn with twenty or thirty
experiences that there was a glass at the bottom to
be avoided. Thinking that there might be an insufficient
motive for escape to effect the formation of an association,
I tried stimulating the subject with a stick as soon
as it was placed in the box. This frightened
it and caused violent struggles to escape, but instead
of shortening the time required for escape it greatly
lengthened it. Here was a case in which the formation
of an association between the appearance of the upper
part of the clear space and the satisfaction of escape
from danger would have been of value to the frog,
yet there was no evidence of adaptation to the new
conditions within a reasonably short time. There
can be little doubt that continuation of the training
would have served to establish the habit. This
very clearly shows the slowness of adaptation in the
frog, in contrast with the rapidity of habit formation
in the cat or chick; and at the same time it lends
additional weight to the statement that instinctive
actions are all-important in the frog’s life.
A few things it is able to do with extreme accuracy
and rapidity, but to this list new reactions are not
readily added. When put within the box described,
an animal after having once escaped would sometimes
make for the opening as if it knew perfectly the meaning
of the whole situation, and yet the very next trial
it would wander about for half an hour vainly struggling
to escape.